function selection()
%
%

c=datac('control'); % get control data base.

[EC, lEC] = unique_arg({c.E_C});
[pnd, lpnd] = unique_arg({c.pnd});
[div, ldiv] = unique_arg({c.div});
[G1, lG1] = unique_arg({c.G1});
[G2, lG2] = unique_arg({c.G2});

EC
pnd
div
G1
G2

function [res, list] = unique_arg(arg)

% from cell array, find unique arguments in list -
% convert numbers to text
% return is cell array 
for i = 1:length(arg)
   if(isempty(arg{i}))
      arg{i} = 'missing';
   end;
   if(isnumeric(arg{i}))
      arg{i} = num2str(arg{i});
   end;
end;
list = arg; % save modified list with indices.
res = unique(arg);
